If you want to change the sprite if you use this anywhere you plan, just change the sprite of the state 463 - S_BLACKEGG_MISSILE to anything you want (or custom) and set the frame to it's idle.

If you want the object to be destroyed on crashing change the thing 42 - MT_BLACKEGGMAN_MISSILE's death state to 258 - S_BPLD1 or you can make your own. Also change the death sound for sfx during crash.